A simple, sensitive and rapid method for flow injection with chemiluminescence analysis has been developed for the determination of prednisone acetate at trace level. This method is based on the luminescent properties of the tris(1,10-phenanthroline) ruthenium(II)-potassium permanganate -prednisone acetate in acidic medium sensitized by Na2SO3. The optimized experimental conditions are evaluated. Under the optimum experimental conditions, the linear ranges of prednisone acetate are: 4.0×10-10~4.0×10-8 g·mL-1 and 4.0×10-8~2.0×10-7 g·mL-1 with a low detection limit is 4.5×10-11 g·mL-1 and the relative standard deviation for 1.0×10-8 g·mL-1 sample is 1.04% (n=11). The proposed method has been successfully applied to the determination of prednisone acetate in tablets.